(i) Field of the Invention
The present invention relates to a modular plug to be fitted into a modular jack, particularly to a modular plug for connecting twisted pair wires each of which is formed by twisting two electric wires.
(ii) Description of the Related Art
In general, as connector members used in a telephone system and a LAN (Local Area Network), a modular jack and a modular plug are known. The modular plug is a member which is fitted into the modular jack so as to connect a plurality of electric wires such as cables. An example of conventional modular plugs is disclosed in Japanese Patent Application Laid-Open No. 134903/1998.
As shown in FIGS. 16 and 17, a modular plug 1 generally comprises a housing 2, an alignment member 3 which is fitted into the housing 2, a guide plate 4 which is fitted to the base end side of the alignment member 3 of the housing 2, terminals 8 and 9 which are connected to eight electric wires 7a, 7b, 7c, 7d, 7e, 7f, 7g and 7h untwisted from four pairs of twisted pair wires 6A, 6B, 6C and 6D of a cable 5, and an insulation case 10.
The housing 2 comprises a shield plate 11 and an insulation portion 12 which is provided on the front end side of the shield plate 11. The insulation portion 12 has eight slits 13 at the front end. Further, the shield plate 11 has a clamp portion 14 extending to the base end side. The alignment member 3 has a horse-shaped cross section. The alignment member 3 also has eight through holes 15a, 15b, 15c, 15d, 15e, 15f, 15g and 15h corresponding to the electric wires 7a, 7b, 7c, 7d, 7e, 7f, 7g and 7h, respectively. The through holes 15 are formed alternately at an upper level and a lower level such that a through hole 15 and its adjacent through hole(s) 15 are at the different levels. Further, the guide plate 4 has four through holes 16A, 16B, 16C and 16D corresponding to the twisted pair wires 6A, 6B, 6C and 6D, respectively. The through holes 16 have a larger diameter than the through holes 15. The through holes 16 are formed alternately at an upper level and a lower level such that a through hole 16 and its adjacent through hole(s) 16 are at the different levels.
To assemble the modular plug 1 which has such a constitution, firstly, the cable 5 is passed through the insulation case 10 from the base end side, the four pairs of twisted pair wires 6A, 6B, 6C and 6D are then passed through the through holes 16A, 16B, 16C and 16D, respectively, and the eight electric wires 7a, 7b, 7c, 7d, 7e, 7f, 7g and 7h are then passed through the through holes 15a, 15b, 15c, 15d, 15e, 15f, 15g and 15h, respectively. Thereby, the four pairs of twisted pair wires 6A, 6B, 6C and 6D are held in the guide plate 4 separately from one another, and the eight electric wires 7a, 7b, 7c, 7d, 7e, 7f, 7g and 7h are held in alignment in the alignment member 3. Then, the alignment member 3 holding the electric wires 7 and the guide plate 4 holding the twisted pair wires 6 are fitted into the housing 2, and then the cable 5 is clamped therearound by the clamp portion 14. Then, the terminals 8 and 9 are inserted into the slits 13 from the outside of the housing 2 and connected to the eight electric wires 7a, 7b, 7c, 7d, 7e, 7f, 7g and 7h. 
In general, modular plugs are demanded to have so-called crosstalk reduced so as to prevent the occurrence of problems such as noises. In recent years, in particular, requirements for the attenuation of near end crosstalk (NEXT) have been becoming increasingly stringent. However, the above conventional modular plug 1 has a possibility that it may fail to meet the recent stringent requirements for the attenuation of the near end crosstalk.
Under the circumstances, the present invention intends to provide a modular plug which can meet such stringent requirements for the attenuation of the near end crosstalk.